The role of dendrin in glomerular disease progression

 描述（由申请方提供）：确定适当治疗靶点以治疗肾小球疾病的关键障碍是对调节足细胞损伤和肾存活的信号级联的理解有限。我们的长期目标是通过阐明调节足细胞损伤和存活的关键信号通路的细节和功能意义来增强可用于解决人类肾小球疾病的推定治疗靶点的管道。我们的初步数据已经确定，树突状蛋白作为一个关键的促损伤信号分子，促进足细胞耗竭，并参与足细胞系膜细胞串扰。我们已经鉴定了与家族性类固醇耐药局灶节段性肾小球硬化症（FSGS）分离的人类树突状蛋白基因变体，并鉴定了促存活Hippo通路效应子Yes相关蛋白（雅普）作为树突状蛋白功能的抑制剂。本申请的总体目标是确定dendrin作为致病性足细胞系膜细胞串扰和随后的肾小球疾病进展的关键介质的作用，我们的中心假设是dendrin以磷酸化依赖的方式由雅普调节，其中疾病相关的dendrin突变体可能通过降低雅普抑制而诱导足细胞损伤。Dendrin调节足细胞可溶性因子促进系膜细胞纤连蛋白分泌，导致系膜基质扩张和肾小球疾病进展。提出的研究的基本原理是，定义树突状蛋白功能如何被雅普抑制，并表征其在肾小球疾病进展中的作用，将促进对肾小球疾病进展的理解，以及对可用于临床的新型治疗靶点的探索。我们的假设将通过追求两个具体目标进行测试：目标1将探索雅普对野生型和FSGS相关树突状蛋白突变体的抑制。我们将定义磷酸化的雅普和树突状蛋白亚型之间的分子相互作用，并表征结合在细胞存活和树突状蛋白亚细胞定位和功能的背景下的后果。我们还将在体内测试足细胞中雅普的转基因表达是否通过抑制树突素功能来减缓小鼠肾小球疾病的进展。在目标2中，我们将使用我们新建立的体外细胞系统以及可诱导的转基因小鼠串扰模型来定义树突素在致病性足细胞系膜细胞串扰中的作用。我们的创新方法利用最先进的蛋白质组学技术来鉴定来自足细胞的树突状蛋白调节的可溶性因子，其诱导系膜细胞纤连蛋白分泌。这些贡献是重要的，因为它们代表了一系列研究的第一步，这些研究有望促进对肾小球疾病进展的理解，并确定改善临床结局的治疗靶点和策略。

 DESCRIPTION (provided by applicant): A critical barrier to the identification of appropriate therapeutic targets to treat glomerular disease is the limited understanding of signaling cascades that regulate podocyte injury and renal survival. Our long term goal is to enhance the pipeline of putative therapeutic targets available to tackle human glomerular disease by elucidating the details and functional significance of key signaling pathways that regulate podocyte injury and survival. Our preliminary data have identified dendrin as a key pro injury signaling molecule that promotes podocyte depletion and is involved in podocyte mesangial cell crosstalk. We have identified human dendrin gene variants that segregate with familial steroid resistant focal segmental glomerulosclerosis (FSGS) and identified the pro survival Hippo pathway effector Yes associated protein (YAP) as an inhibitor of dendrin function. The overall objective of this application is to define the role of dendrin as a key mediator of pathogenic podocyte mesangial cell crosstalk and subsequent glomerular disease progression.Our central hypothesis is that dendrin is regulated in a phosphorylation dependent manner by YAP, where disease associated dendrin mutants may induce podocyte injury though decreased YAP inhibition. Dendrin regulated soluble factors from podocytes promote mesangial cell fibronectin secretion, leading to mesangial matrix expansion and glomerular disease progression. The rationale for the proposed research is that defining how dendrin function is inhibited by YAP and characterizing its role in glomerular disease progression will advance understanding of glomerular disease progression as well as the quest for novel therapeutic targets available for clinical use. Our hypothesis will be tested by pursuing two specific aims: Aim 1 will explore the inhibition of wild type and FSGS associated dendrin mutants by YAP. We will define the molecular interaction between phosphorylated YAP and the dendrin isoforms and characterize the consequences of binding in the context of cell survival and dendrin subcellular localization and function. We will also test in vivo whether transgenic expression of YAP in podocytes slows murine glomerular disease progression by inhibiting dendrin function. In Aim 2 we will define the role of dendrin in pathogenic podocyte mesangial cell crosstalk using our novel established in vitro cell systems as well as an inducible transgenic mouse model of crosstalk. Our innovative approach utilizes state of the art proteomics technology to identify dendrin regulated soluble factors from podocytes that induce mesangial cell fibronectin secretion. These contributions are significant because they represent the first step in a continuum of research that is expected to advance understanding of glomerular disease progression and identify therapeutic targets and strategies to improve clinical outcomes.